It is known that a conventional voltage regulator can be used to regulate a DC voltage supplied to a load such as a microprocessor. For example, a voltage regulator can include a power converter, such as a DC-DC converter, and may include other components such as a controller for controlling operation of the power converter.
An example of a DC-DC converter is a synchronous buck converter, which has minimal components, and therefore is widely used in voltage regulator applications. In an example application, the input voltage to the buck converter is typically 12VDC. An output voltage produced by the voltage regulator may be 5.0VDC, 3.3 VDC, or even lower.
Conventional multiphase interleaved voltage regulator power supply topologies can include two or more power converter phases that operate in parallel with each other to convert power and supply power to a corresponding load. Implementation of a multiphase voltage converter topology (as compared to a single voltage converter phase topology) can therefore enhance the output current capability of a power supply system.
A typical configuration of a voltage regulator such as a so-called synchronous buck converter includes an inductor, a high side switch, and a low side switch. During operation, a controller associated with the buck converter repeatedly pulses the high side switch ON to convey power from a power source through the inductor to a dynamic load. The controller repeatedly pulses the low side switch ON to provide a low impedance path from a node of the inductor to ground in order to control an output of the buck converter. Thus, the energy stored in the inductor increases during a time when the high side switch is ON and decreases during a time when the low side switch is ON. During switching operation, the inductor transfers energy from the input to the output of the converter phase.
In today's computer applications, respective processors (e.g., a load) can require activation of anywhere from 1 to 8 phases to power a load. In typical cases, phases are parallel, pulse-width modulated (PWM) buck converter channels, running at the same frequency but at a different phase angle.
According to conventional analog controllers, as the number of phases of a buck converter increases, the circuitry needed for pulse generation is replicated for each additional phase. For example, a first circuit is used to control timing and generate a pulse width modulation signal to control a first phase, a second circuit is used to control timing and generate a pulse width modulation signal to control a second phase, and so on. Each circuit generally operates independently, except the phases are controlled to be offset from each other. Thus, a conventional analog controller circuit for a multi-phase power supply can occupy a substantial amount of real estate on a printed circuit board, especially when many phases are implemented. Note also that there is considerable cost incurred for the electrical components implemented in the controller circuit, which also increases when implementing many phases.
In an analog controller, the PWM modulator typically consists of a precision ramp generator, a comparator, and a flip-flop and control logic. For large numbers of phases (such as greater than 4) it is difficult and costly to design in the ramp generators and comparators to have required precision and matching.